<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<script>
    let score = 80;
    if (score > 80) {
        console.log("Good");
    } else {
        alert("not bad");
    }
    let a = 1.121e3;
    let b = "1.121e3";
    console.log(a === b);
    console.log(isNaN(NaN));

    console.log((1 - 1 / 3) === 2 / 3);
    let x =Math.abs((1 - 1 / 3) - 2 / 3 ) < 0.0000001;
    console.log(x);

    let arr = [1, 2, 3, "string", null, true];
    console.log(arr[4])

    let person = {
        name : "chen",
        age : 18,
        hobby : "study"
    }
</script>

</body>
</html>